Gene-environment interactions may be major contributors to Parkinson's disease (PD) etiology, however this area of research has been severely hampered by the relatively small sample size of most population-based PD studies and/or a lack of valid and standardized exposure assessment across studies. We will take advantage of a worldwide unique resource available in Denmark to conduct the largest population-based case-control study ever to examine gene-environment interactions in PD: the National Parkinson's Patient Register in Denmark. We propose to recruit actively and prospectively approximately 2500 recently registered incident PD patients and 2,500 age-gender matched controls from the Danish population to collect risk factor information per interview and biological materials for genetic analyses. All patients will be examined and characterized clinically and phenotypically by a trained movement disorder fellow. We will examine 1) which lifetime occupations and occupational exposures are associated with PD;specifically, we will evaluate farming and greenhouse occupations (pesticides), metal related industries (metals and solvents), and night shift work (melatonin levels);2) whether certain drugs and medical conditions are positively or inversely associated with PD (e.g. NSAIDS, aspirin, and cortisone use, or M. Crohn and colitis and rheumatoid arthritis) through their potential to induce chronically low iron levels and induce/reduce systemic inflammation;and 3) previously identified factors including smoking, alcohol use, dietary nutrients and contaminants (such as pesticides and metals from fish consumption), and physical activity. Most importantly, we will examine whether functional polymorphisms of metabolic and PD specific candidate genes differentially influence risks associated with environmental factors. As a secondary aim we will also employ passive record linkage by unique ID to link data from the National Patient Register, Pharmacy Database, and National Pension fund to identify risk factor information contained in these records (e.g. occupations, medication use, and diseases prior to PD onset) for approximately 13,000 PD cases diagnosed since 1983 and age-gender matched controls from the Danish population. The proposed research cannot be performed in the US due to a lack of population PD registries that would provide access to such a large number of cases and valid methods for control recruitment from the general population.